Answer:
50, read the first paragraph to get a feel for how to calculate it. If you don't understand it though let me know.
Step-by-step explanation:
There may be a formula for this, but I am just going to logic it out.
So in total there are 900 people. If the sampling was asking for 900 total then we would just be able to use everyone. if instead the sample wanted to use 450 we would only take half of each town since 450 is half of 900. To check let's take half of each town and add them up. 300/2 = 150, 350/2 = 175 and 250/2 = 125. 150 + 175 + 125 = 450. So you can kee this going, say you wanted 180, which is 1/5 of the total, you would take 1/5 of each of the towns. So the point is to find how much the sample is compared to the total.
Now for your question, the total is 900 and we want 150. How much of this is 900? Basically you want to solve 900/x = 150. or in other words 900/150 = x = 5. So that means we want to take a fifth of each town.
Specifically the question is asking for Z so we just have to find that. Total population of Z is 250, so we want 1/5 of that. so 250/5 = 50.
I hope that all made sense, let me know if it didn't though, I'm happy to explain.
